The present invention relates to devices for sequentially feeding elongated bodies, such as beams, timber, planks, or the like, to a conveyer.
In the handling of beams, such as timber beams cut by suitable saws from logs so as to have a predetermined length, width, and thickness, it is often necessary to feed the beams one-by-one at a given distance from each other into a machine such as a sorting machine. When attempting to increase the capacity of such machines, a limiting factor is encountered in connection with a limitation on the speed with which the beams can be fed. The reason for this is that at high feeding speeds on the order of over one hundred timber beams per minute, the beams do not remain stable but instead are inclined to jump or tilt. Thus, the beams are initially arranged in an uninterrupted layer wherein the beams are situated in a row, extending transversely of the row, and directly engaging each other. During high feeding speeds as set forth above the beams in such a layer tend to tilt with respect to the layer or jump out of the layer.
Attempts have already been made to avoid this drawback. For example, reference may be made to Finnish Patent No. 43,564 and Swedish Patent No. 325,299. According to these patents a movable barrier is lowered toward the layer to prevent occurrences as set forth above, but the fact that the timber beams move primarily horizontally with such devices results in a serious limiting of the speed with which the beams can be fed to a conveyer.
While Finnish Pat. No. 48,569 also shows a structure tending to solve this problem, this structure is not suited for planed timber beams because the structure of this patent has grabbers provided with spikes which mar the surfaces of the beams.
When feeding small or planed, previously sawed timber beams at high speed, particularly under icy conditions, the most effective feeding has proved to be one where the timber is fed by being lifted from the timber layer because in such case suitable picker lines can be utilized while being situated close to each other and the quantity of timber beams fed sequentially in a given unit of time would be relatively large although the picking speed is relatively slow and the feeding operations are relatively quiet.
However, with procedures as set forth above, a particular defect has been encountered with respect to the friction between a beam which is being transported from the layer to a conveyer and the next beam, this friction being so great that the beam next to the one which is being fed turns or tilts or moves in some other way from its proper position, thus resulting in a breakdown of the feeding operations. Often such breakdowns result in interrupting the whole production line for a considerable interval.
While efforts have been made to avoid this problem by mounting barriers over the beams next to their upper surface, this expedient is disadvantageous in that it requires additional structure which also causes undesirable breakdowns in the operations particularly when timber beams of an improper size are fed.